Method for retrieving predetermined locations in sewer and pipeline systems

ABSTRACT

The present invention relates to a method for retrieving predetermined locations in sewer and pipeline systems ( 7 ) after the application or the deposition of a layer of material, in which a carrier vehicle having a microwave sensor ( 1 ) is used which emits microwave signals and receives backscattered microwave signals, having the following steps. In the method a first run is conducted inside the sewer respectively the pipeline system ( 7 ) is conducted before the application or the deposition of the layer of material, with in at least one section of said sewer respectively pipeline system a first temporal signal profile of said backscattered microwave signals being recorded and the sought locations being marked in the first signal profile. After the application or the deposition of the layer of material, a second run is conducted in which a second temporal signal profile of said backscattered signals is recorded and the current position of the carrier vehicle in the sewer respectively the pipeline system ( 7 ) relative to the sought locations being determined by comparison with said first signal profile.  
     The method permits certain retrieval and sufficiently accurate localization of house connection or other sites which are covered by inliner pipes or deposits.

TECHNICAL FIELD

[0001] The present invention relates to a method for retrievinglocations in sewer and pipeline systems following the application or thedeposition of a layer of material by utilizing a carrier vehicle havinga microwave sensor that emits microwave signals and receivesbackscattered microwaves. The invented method is particularly suited foruse in the field of intelligent TV and sensor-based sewer and pipeinspection and renewal.

STATE OF THE ART

[0002] In the renewal of sewer and pipeline systems, such as for examplesewer pipes in public and communal pipeline networks, frequentlyadditional so-called in-liner pipes made of plastic material areinserted into the to-be-renewed pipe sections. However, when insertingthese new inliner pipes to renew defect pipe sections, all houseconnections entering the pipe are covered. In a subsequent step, a piperobot has to mill the covered connections free using a maneuverablemilling head.

[0003] Presently, in order to locate these covered house connections,information about its known location from drawn from plans respectivelypreceding travelling along the pipe is utilized and the robotrespectively the carrier vehicle bearing a milling head is positionedaccordingly in the sewer respectively the pipeline system using itspath-giver sensors.

[0004] A sufficiently accurate and reliable positioning of the millingtool before the covered house connection however still presentsconsiderable problems with this state of the art technology. Determiningthe positioning only by means of the path-giver sensors of a reelattached to a robot respectively the robot itself have proven to be tooinaccurate. Moreover, these values can be falsified by the robot's driveslip. Incorrect borings and thus expensive damage to the inserted inlinepipe and the sewer pipe underneath are often the consequence.Furthermore, operator errors can occur with this type of positioning bythe operator steering the robot from outside the sewer and pipelinesystem.

[0005] DE 19600085 A1 discloses a method for detecting holes in a pipe,in which a radar device moves along the inside the pipe along itslongitudinal axis and emits signals transverse to the direction ofmovement and receives reflected signals. Holes, such as for examplehouse connections can be localized, even after insertion of an inlinerpipe, by means of subsequent evaluation of the reflection signals.However, the complex signal profile of the received signals makes thisdirect detection of holes in a pipe very expensive and susceptible toerrors. Furthermore, this technology does not permit locating a randomnumber of predetermined sites in the pipeline system.

[0006] The object of the present invention is to provide a method forrelocating covered house connections or other sites in sewer andpipeline systems, which offers a great reliability and accuracy.

DESCRIPTION OF THE INVENTION

[0007] The object is solved using a method according to claim 1Advantageous embodiments of the method are the subject matter of thesubclaims.

[0008] In the present method, a carrier vehicle having a microwavesensor is employed, which emits microwave signals and receivesbackscattered microwave signals, for example a microwave backscattersensor (MRS), as is known from DE 4340059 C2 for use signal profile ofthe received signals makes this direct detection of holes in a pipe veryexpensive and susceptible to errors. Furthermore, this technology doesnot permit locating a random number of predetermined sites in thepipeline system.

[0009] DE 195 21 895 A discloses a comparable method for retrievingpredetermined locations in sewer and pipeline systems after theapplication or the deposition of a layer of material, in which a carriervehicle having a microwave sensor is utilized which emits microwavesignals and receives backscattered microwave signals.

[0010] This method also has the previously described disadvantages.

[0011] The object of the present invention is to provide a method forrelocating covered house connections or other sites in sewer andpipeline systems, which offers a great reliability and accuracy.

DESCRIPTION OF THE INVENTION

[0012] The object is solved using a method according to claim 1.Advantageous embodiments of the method are the subject matter of thesubclaims.

[0013] In the present method, a carrier vehicle having a microwavesensor is employed, which emits microwave signals and receivesbackscattered microwave signals, for example a microwave backscattersensor (MRS), as it known from DE 4340059 C2 for use for the inspectionof sewer and pipeline systems. However, of course, any other microwavesensor can be utilized. In the present application, carrier vehiclerefers to any type of transport means in sewer or pipeline systems, forinstance also pneumatic-based pipe worms.

[0014] First, prior to the application or the deposition of a layer ofmaterial, a first run of the carrier vehicle inside the sewer orpipeline system is conducted in which the sought locations are detectedby means of an imaging system, with a first temporal signal profile ofthe backscattered microwave signals, preferably amplitude and relativephase, is recorded in at least one section of the sewer or pipelinesystems and the sought sites, such as for example house connections orspecific markings on the inside wall of the pipe are marked in the firstsignal profile. Recording occurs preferably by transmitting the detectedbackscattered signals to a data processing station located outside thesewer respectively pipeline system. An operator sitting at this dataprocessing station steers the carrier vehicle by remote control.Transmission may occur via a cable in real time.

[0015] It is not necessary to record the backscattered signals along theentire sewer or pipeline system. But rather it suffices to record in asection in which the interesting respectively sought sites are located.Marking in the signal profile occurs preferably by the operator pressingthe appropriate button during data transmission as soon as the carriervehicle is situated at the corresponding position and, if required, thecorrect roll angle of the setup with the microwave sensor located on thecarrier vehicle is set. As an alternative, marking can occurautomatically or semi-automatically using a reference measurementsystem. The recorded data are stored.

[0016] After the application or the deposition of the layer of material,a second run of the carrier vehicle is conducted. During the run, asecond temporal signal profile of the system vehicles. However, otherimaging systems can, of course, also be used, for example ultrasonicimaging systems, as long as the operator can detect the sought locationsin the transmitted images.

[0017] Various possibilities of carrying out the invented method forretrieving covered house connections are described in the following.However, other alternatives than the described ones are, of course, alsoavailable to someone skilled in the art.

[0018] Sufficiently accurate localization of the covered houseconnections respectively of subsequent positioning of the milling toolrequires two successive runs. The first run, referred in the followingas the reference run, occurs before insertion of the inliner pipe andhas the purpose to accurately measure the position of the not coveredhouse connections using the robot's path giver. The second run, in thefollowing referred to as the detection run, occurs after the insertionof the inliner pipes. During this run, the signal profile of thebackscattered microwave signals is recorded again. Intelligentcomparison, of the current measured signal profile and the signalprofile recorded and stored during the reference run using suitedmethods, for example prior art correlation methods, permits correctingdeviations of the path giver from the first run. The stored position andorientation of the covered house connections can be relativelyaccurately localized in this manner,

[0019] For the reference run, there are two possible manners ofproceeding:

[0020] 1. In operator-controlled referencing, the operator travels toeach house connection individually and marks in the recording, forexample by pressing a button, that, e.g. the camera is located exactlyat the house connection position. The roll angle can also either bemoved to directly with the camera or entered manually. run, can becorrected at any time. The characteristic signal pattern is independentof the accuracy of the employed path giver and of the drive concepts andalways delivers accurate information for retrieval of the coveredlocations.

[0021] The carrier vehicle is equipped with an imaging device whichtransmits images of the interior of the sewer respectively pipe systemin real time to a receiving station located outside the sewerrespectively outside the pipeline system where the operator can detectthe sought locations with the aid of the transmitted images and marksthem in the signal profile. Particularly suited as the imaging system isa TV camera like those already attached to prior art pipe inspectionvehicles. However, other imaging systems can, of course, also be used,for example ultrasonic imaging systems, as long as the operator candetect the sought locations in the transmitted images.

[0022] Various possibilities of carrying out the invented method forretrieving covered house connections are described in the following.However, other alternatives than the described ones are, of course, alsoavailable to someone skilled in the art.

[0023] Sufficiently accurate localization of the covered houseconnections respectively of subsequent positioning of the milling toolrequires two successive runs. The first run, referred in the followingas the reference run, occurs before insertion of the inliner pipe andhas the purpose to accurately measure the position of the not coveredhouse antennas 3 are arranged staggered in the longitudinal direction,with the axes of the directional characteristic of transmission antennas2 being aligned at an angle of approximately 45-60° to the longitudinalaxis of the inspection robot, whereas the axes of the directionalcharacteristic of the reception antennas 3 run perpendicular to thislongitudinal axis. Such an arrangement largely suppresses undesiredreflection signals from the pipe wall 6 so that the backscatter signalscan be detected with greater sensitivity. FIG. 1 shows, by way ofexample, in a schematic representation the emitted signals reflected atan object 4, at the pipe bottom 5.

[0024] In an alternative embodiment, as shown in FIG. 2, it is alsopossible to only provide a rotary transmitting antenna 2 and a rotaryreceiving antenna 3, which are turned about the axis of the pipe.

[0025] The inspection robot is composed of a carrier vehicle on which aTV camera is arranged next to the MRS module. The carrier vehicle isconnected via a trailing cable to a PC control station located outsidethe pipe. An operator sits at this PC control station who steers theinspection vehicle and the camera located thereon. The purpose of thetrailing cable is, on the one hand, to supply the vehicle with energyand to transmit control signals to the vehicle and, on the other hand,to transmit camera signals and sensor signals from the vehicle. In thecase of long pipe distances with a slippery bed, movement of the vehiclecan be supported via an additionally provided power controlled hoistingwinch, a reel.

[0026] Data communication with the PC occurs via a standard serialcommunication line with 19.2 Kbaud. As the amount of data picked up withthe MRS module during a quick inspection run is too great for real-timetransmission over this serial connection, the MRS signals are stored inthe MRS module for a period of, e.g. 100 s (approximately 1 Mbyte). At avehicle velocity of 3 m/min, this corresponds to an inspection route of5 m. The data are then transmitted via the communication line to the PCcontrol station as required. During this time the vehicle can remainstanding, e.g. after passing a house connection. The detection run ispreferably conducted with less speed in the interesting sewer section sothat the data of this section can be transmitted in real time.Digitalization and, it required, intermediate storage of the MRS dataoccurs on the inspection robot, storage and evaluation of the data onthe control PC. Of course, transmission of the data can also occur overother, in particular faster, connections so that real-time transmissionis realizable even with faster vehicle velocity.

[0027] In carrying out the method, the operator first conducts areference run with the inspection system before inserting the inlinerpipe. In this reference run, he travels to all the house connections(individually). During the entire run, the MRS module picks up thebackscatter signals of the emitted microwaves. The amplitude and phase(relative to the emitted CW microwave signals) of the received signalsare detected dependent on the path-roll angle profile of the inspectionvehicle. This profile information is available to the system via thepath giver on the inspection vehicle. The control in the vehicle givesthe MRS module, via a start signal (reset) and a path pacer respectivelya time pacer, the path markers required for data buffering.

[0028]FIG. 3 shows, by way of example a signal profile of the amplitude(bottom figure) an the phase (top figure) of the backscattered microwavesignals dependent on the covered path and its reproducibility (in thefigure with 5 identical measurement runs in a pipe). The position of ahouse connection is marked with an arrow. The characteristic profile ofthe signals, from which the position of the house connections can belocated in the detection run, can be very readily identified.

[0029] The operator locates the position of the house connections fromthe images provided by the camera. The operator positions the camera,for example, perpendicular to the axis of the pipe and centers thecamera with the vehicle and the roll angle in relation to the houseconnection. Upon assuming this position, the camera informs the MRSevaluation program that the camera is situated exactly at the positionwhere the house connection is located. In this manner, this position canbe allocated to a measured position on the path axis respectively thepath-roll angle profile of the determined microwave data.

[0030] After recording these data, the inliner pipe can be inserted.Then the detection run with the inspection system is conducted. In thiscase, too, the signal profile of the MRS sensor is recorded via therobot's path-roll-angle profile during the straight ahead run. Thedetermined data are continuously transmitted during the run to thecontrol PC, which compares the signal profile with the previouslyrecorded profile with the aid of a correlation method and using themarked signal pattern detects in this manner at any time the currentposition of the inspection vehicle relative to the next house connectionindependent of whether the path giver operates accurately or there aremajor uncertainties due to slip. Possible extension or compression ofthe signal profile due to varying slip is compensated in this manner.Upon reaching the covered house connection detected by means of thesignal profile, the house connection is marked in color on the interiorof the pipe by means of the marking device provided on the robot and therun is continued. Following marking the connections, a robot vehiclewith a milling head and a TV camera can then enter the pipe and lay barethe house connection at the marked sites.

[0031] With the invented method, covered house connection pipes (DN 100to 200) can be reliably and accurately detected respectively locatedagain in sewer pipes (DN 300 to 500). By using a LSS sensor deviationsin shape, for example bulging of the inliner over the house connectioncan be optimally detected and utilized as further evidence of a coveredhouse connection.

LIST OF REFERENCE NUMBERS

[0032] 1 microwave backscatter sensor

[0033] 2 transmitting antenna(s)

[0034] 3 receiving antenna(s)

[0035] 4 object

[0036] 5 pipe bed

[0037] 6 pipe wall

[0038] 7 sewer

[0039] 8 dielectric structure of the sewer surroundings

What is claimed is:
 1. A method for retrieving predetermined locationsin sewer and pipeline systems after the application or the deposition ofa layer of material, in which a carrier vehicle having a microwavesensor (1) is used which emits microwave signals and receivesbackscattered microwave signals, characterized by having the followingsteps: conduction of a first run inside said sewer respectively saidpipeline system (7) with said carrier vehicle before said application orsaid deposition of said layer of material in which said sought locationsare detected by means of an imaging system, with in at least one sectionof said sewer respectively pipeline system (7) a first temporal signalprofile of said backscattered microwave signals being recorded and thesought locations being marked in said first signal profile; andconduction of a second run with said carrier vehicle after saidapplication or said deposition of said layer of material, with a secondtemporal signal profile of said backscattered signals being recordedduring said run and the current position of said carrier vehicle in saidsewer respectively said pipeline system (7) relative to said soughtlocations being determined by comparison with said first signal profile.2. A method according to claim 1, wherein said first and said secondsignal profile include the amplitude and phase of said backscatteredmicrowave signal.
 3. A method according to claim 1 or 2, wherein amicrowave backscatter sensor (1) is utilized as said microwave sensor.4. A method according to one of the claims 1 to 3, wherein saidmicrowave signals are amplitude modulated.
 5. A method according to oneof the claims 1 or 2, wherein a radar sensor, which preferably runs inFM-CW or pulse radar operation, is utilized as said microwave sensor(1).
 6. A method according to one of the claims 1 to 5, wherein saidimaging system is a camera, if required, with an additional lightsection sensor.
 7. A method according to one of the claims 1 to 6,wherein said comparison is carried out using a correlation method.
 8. Amethod according to one of the claims 1 to 7, wherein said first andsaid second temporal signal profile are normed on a path-roll-angleprofile of said carrier vehicle respectively of said microwave sensor(1) on said carrier vehicle.
 9. A method according to claim 8, whereinthe path is determined from a path-giver signal of said carrier vehicleor via a cable drum connected with it by a cable.